1,3-propanediol is mainly used as a monomer, to build polymer PTT (polytrimethylene terephthalate) used in production of fibers, carpets, textiles for sanitary and medical applications, and as a packaging and/or structural material.
Techniques for extraction of 1,3-propanediol from post-fermentation broth, obtained from a fermentation process have drawbacks and may benefit from improvement.
U.S. Pat. No. 7,056,439 discloses a method for extraction of 1,3-propanediol from fermentation broth with alcohols (pentanol, propanol, hexanol, oleyl alcohol), ketones (4-methyl-2-pentanone), esters (isopropyl acetate, tributyl phosphate), oleic acid, soybean oil, alkanes (n-hexane) and mixtures thereof. This method requires multiple extraction with different solvents and reverse extraction to aqueous phase. Maximum purity of isolated 1,3-propanediol using this method is 95-98.5%.
U.S. Pat. No. 5,008,473 describes a method for isolation of 1,3-propanediol with cyclohexane.
European Patent Application No. 1,720,814 B1 shows a method for isolation of hydrophilic organic compounds, including 1,3-propanediol, with glycol ether at a temperature and then as a result of heating to a higher temperature to obtain an aqueous extract with hydrophilic compound and ether rafinate. The method is based on extraction with ether glycols and a phenomenon specific for them of decreasing the ether solubility in aqueous phase with the increase of temperature. The method discloses also addition of organic solvents in order to further decrease the glycol ethers solubility in aqueous phase during a reverse extraction step to aqueous phase. Among additives some ketones are mentioned. In this method organic solvent is not used alone for extraction per se. This function is fulfilled by glycol ether, that by nature, forces the temperature increase and reverse extraction to aqueous phase. The whole solution thus constitutes the concentration of 1,3-propanediol in aqueous phase, as in U.S. Pat. No. 7,056,439.
U.S. Patent Publication 20120184783 discloses a process for purification of particular diols, including 1,3-propanediol, from diols mixture by extraction with an organic solvent or a mixture of organic solvents. A proper selection of solvent mixture allows recovery of a selected diol group (comprising three, four and five carbon atoms), from the starting mixture, where content of water is max. 50 wt. %.
Chinese Patent Application No. 101012151A describes a method of 1,3-propanediol isolation from post-fermentation broth containing trimethylene glycol in the range of (30-700 g/L) comprising an initial saturation with inorganic salts (10-100%) and organic solvent addition for extraction.
Chinese Patent Application No. 1907929 discloses a method of isolation of 1,3-propanediol from fermentation broth containing trimethylene glycol by extraction combined with chemical reaction. The recovery of 1,3-propanediol is made after hydrolysis and distillation.
A similar recovery technique is presented by Malinowski et al. (Biotechnol. Prog., 16: 76-79, 2000). This extraction is based on isolation of 1,3-propanediol by extraction with aldehydes, as reactants, converting 1,3-propanediol into alkyl dioxane and the product is next extracted with organic solvents (toluene, o-xylene, ethylbenzene).
A process of 1,3-propanediol extraction from post-fermentation broth with mixture of ethyl acetate and ethanol is known from Separation Science and Technology, 45: 541-547, 2010.
1,3-propanediol can also be recovered by continuous liquid-liquid extraction (Biotechnol. Tech., 13: 127-130, 1999).
Chinese Patent Application No. 1460671A discloses a step of thermal concentration for reduction of volume of the post-fermentation broth (containing the product) and biomass removal step by precipitation with organic solvent. Liquid-liquid extraction and aqueous/organic phase mixing are not mentioned. Mixing is performed only during biomass washing after precipitation. Methyl-ethyl ketone is added, as a precipitating agent, only to remove the biomass, but not as the extractant. This is evidenced by absence of phase distribution (aqueous/organic) and extraction of the supernatant was not performed.
Chinese Patent Application No. 1460671A describes a process for distillation of a mixture of water (from post-fermentation broth) and an organic solvent (used for precipitation of biomass). The described approach is lacking in the critical liquid-liquid extraction process.
European Patent Application No. 0261554 A discloses extraction of 1,3-propanediol with cyclohexane.
European Patent Application No. 1103618B1 is based on a known method of ion exchange chromatography, where 1,3-propanediol is isolated using a cationic resin, and in a next step a column of activated carbon and a weak basic anionic resin or cationic resin and strong basic anionic resin.
U.S. Pat. No. 6,603,048 discloses a method of isolation of 1,3-propanediol from post-fermentation broth, which comprises 1,3-propanediol, and other fermentation co-products, (inter alia, glycerol), using molecular sieves, which are zeolites. The process is an example of industrial use of 1,3-propanediol recovery method from the post-fermentation broth. Despite its industrial use, the method uses an expensive separation medium and separation of products on a semi-continuous basis that generates additional capital and production expenses.
Chinese Patent Application No. 101497556A discloses a solid super acidic catalyst method as a method for isolation of 1,3-propanediol followed by aldol condensation reaction, and rectification.